To simply and economically manufacture the model having high precision, high quality and excellent texture by fixing the thin sheetlike stock using an aluminum super plastic alloy on one die and blow-forming with a compressed air under a heating state.

The super plastic Al alloy stock 1 having the thickness of 0.3-0.8mm is suitable for the model. The stock 1 is vertically or horizontally arranged so as to cover the upper surface of one female die 3 arranged within a forming machine 20, and a clamp member 7 provided with a closed chamber 5 is fixed with the upper surface of the die 3 covered. Under this state, the inside of the forming machine 20 is heated with a heater H, the stock 1 is made to be under heating state, the compressed air E is poured, and blow- forming is executed. The working condition of blow-forming is specified that the inside of the forming machine 20 is heated at about 500°C and the air E of about 12-25 atmospheric pressure is poured for about 5-15 minutes. That is, the stock 1 is installed to one die 3 of only one side, and three-dimensional cubic shape of model is manufactured with one time working by blow-forming.